Speaker
Description
In this work, we characterise the frequency stability of a thermally isolated fibre frequency reference in the $0.1\,\mathrm{mHz}$ to $1\,\mathrm{Hz}$ frequency band relevant to laser stabilisation in inter-satellite ranging missions. Inter-satellite ranging using laser interferometry provides the precision of interferometry on a large enough scale that it can be used to probe physical phenomena of interest through gravity. In the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission, a laser ranging instrument demonstrated that the $220\,\mathrm{km}$ separation between two satellites in low-Earth orbit could be used to track mass fluctuations on the surface of the Earth from climate features such as water movement. Inter-satellite ranging is also planned to detect gravitational waves in a frequency band not possible with ground-based detectors in the Laser Interferometer Space Antenna (LISA) mission. The ranging precision in these missions relies on stabilising the frequency of the laser to a stable frequency reference. Currently the technology of choice for achieving this is a Fabry-Perot cavity. However, optical fibre is more robust, inherently aligned, smaller, cheaper and easier to integrate with other systems, and fibre frequency references are not restricted to operating at a specific set of frequencies. This makes fibre frequency references an attractive option for laser stabilisation in future inter-satellite ranging missions. So far, their frequency stability in the $0.1\,\mathrm{mHz}$ to $1\,\mathrm{Hz}$ regime relevant to gravity detection missions has not met the $30\,\mathrm{Hz/\sqrt{Hz}}$ requirement due to thermal coupling to the environment. This presentation will cover our progress and results towards demonstrating a $1\,\mathrm{km}$ delay-line fibre frequency reference with a passive thermal isolation system designed to bring the frequency stability within this requirement.
| I am the presenting author | Yes |
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